This invention relates generally to electrical devices. More specifically, the invention is directed to devices which are capable of de-energizing an electrical circuit.
A typical home today is powered by an electrical system which originates in a service panel. Electricity is distributed from the service panel to a number of branch circuits. The branch circuits feed power to many switches, receptacles, fixtures, and appliances in different areas of the house. The branch circuits are attached to one or two “hot” bus bars, depending on their voltage specification. When a branch circuit is over-loaded, or when a short occurs in some part of the circuit, the associated breaker trips, thereby shutting off power, i.e., “de-energizing” the circuit. In this manner, over-heating of the wiring is prevented, and a dangerous situation is thus avoided.
When a branch circuit has to be serviced or changed, it is a safe practice to shut off the appropriate circuit breaker (or fuse) supplying power. This step can be time-consuming if the breakers in the service panel are unmarked. In many instances, the service panel is located a distance from the electrical outlet being serviced.
Furthermore, many modern houses are much larger than houses of past generations. Thus, the distance to the service panel from the work location can be greater than ever. Moreover, the larger homes are often equipped with ever-greater numbers of televisions, appliances, computers, and the like. Thus, the number of branch circuits required for the home has also increased, resulting in an even longer search for one particular, unmarked breaker.
In a typical situation, a home owner, electrician, or other worker (often working alone) would have to first go down to the service panel and shut off a circuit breaker which might be the correct choice. The individual would then walk back to the work area to determine if the correct branch circuit has been de-energized. If not, the chore will have to be repeated—perhaps several times in a large home.
Electricians and other workers sometimes attempt to manually trip the breaker at an outlet in the branch circuit, so as to avoid the walk to the service panel, and get on with the job at hand. For example, the breaker can often be tripped by sticking opposite ends of a wire into each adjacent slot of an electrical receptacle (sometimes referred to as an “outlet”). The mid-portion of the wire is covered by insulation, and is often held by pliers or a similar tool.
While the make-shift wire tool can sometimes successfully trip the breaker at an outlet, there are some considerable disadvantages to its use. For example, the wire may not be in firm, complete contact with the electrical circuit in the outlet, resulting in arcing and flashback. Very often, the flashback can damage the receptacle. For example, the receptacle face can be charred or discolored, necessitating replacement. Moreover, the underlying components in the receptacle, such as its electrical connections, can be damaged by the flashback. Furthermore, the arcing can represent a physical danger to the individual working near the outlet.
Various devices are available for measuring the electrical characteristics of a branch circuit. For example, an armature tester is described in U.S. Pat. No. 4,893,086 (Shrewsbury). The device includes a housing from which conductive probes extend, and a power source (e.g., a battery) within the housing, for providing voltage across a selected coil winding on the armature being examined. A voltmeter or similar device is provided to detect whether a selected coil is shorted, or has some other characteristic. The tester can include other features as well, such as a rheostat.
The testing device of Shrewsbury appears to be quite useful for assessing the status of an armature coil. However, such a testing device does not appear to be capable of indicating whether a branch circuit is energized, via inspection from an electrical outlet in that circuit. Moreover, the Shrewsbury device has nothing to do with de-energizing a branch electrical circuit.
A device for remotely controlling electricity from one or two electrical supply sources is described by Zerillo, in U.S. Pat. No. 5,036,214. The device includes a receiver-controlled switch mechanism, along with an electrical circuit arrangement for providing and terminating electricity to an outlet of the device. Zerillo's invention apparently permits lamps and appliances to be switched on and off from remote locations, using different power supplies. Zerillo's device includes other features as well. For example, a clock-actuated switch can be incorporated into the device.
The device described in Zerillo's patent appears to be useful for the remote control of various electric power supplies. However, such an invention does not function to measure electrical current at an electrical outlet in a branch circuit. The device also has nothing to do with de-energizing such a branch circuit.
An audible test circuit device is described by R. Brown, in U.S. Patent Application Publication 2002/0057089. The device includes a four-way bridge rectifier circuit contained within a cylindrical body. The rectifier circuit is capable of producing a DC output voltage of known polarity. The device further includes a number of prongs extending from the body, and coupled to the rectifier circuit. The body of the device includes indicator lights. These lights provide a visual indication of power applied to the rectifier circuit, while also indicating the polarity of the circuit being tested.
The test circuit device of Brown further includes an audible alarm. The alarm is also coupled to the rectifier circuit, and is activated when power is applied thereto. Moreover, Brown's device includes a lamp attachment which can be connected to the prongs. In this manner, the test circuit can be attached to a lamp socket, for testing its power and polarity.
The invention of Brown appears to be useful for analyzing a circuit, in terms of electrical power, as well as polarity. However, the Brown device is a testing device—not a device capable of de-energizing an electrical circuit. The title of the publication includes the term “circuit breaker”, but this appears to be a misnomer. Nothing in the mechanism, as described, appears to indicate a circuit breaker function.
In view of the discussion above, it appears that a device which de-energizes a branch electrical circuit would be very welcome in the art. The device should be capable of de-energizing the branch circuit at different locations. For example, it would be very desirable if the device could be used at various outlets and fixtures in one or more rooms served by the circuit in a home or building. Moreover, the device should preferably be convenient and easy to use. A hand-held device would be of great interest, for example.
Furthermore, operation of the device should be very safe for the user, and should not result in damage to the electrical receptacle or any of the underlying components. A de-energizing device which was also capable of detecting whether a branch circuit was “live” or not would additionally be of great interest. Moreover, a de-energizing device which was capable of measuring the actual voltage present in a particular branch circuit would be very advantageous.